Fig. 1. Schematic illustration of DNA-mediated reduction of potassium ferricyanide (K3[Fe(CN)6]) by methylene blue (MB). (a) Workflow for the measurement of target ctDNA. (b) Electrochemical sensing mechanism of the DNA sensor. (c) Background-subtracted square wave voltammograms (SWVs) in the absence and presence of target ctDNA (101 nucleotides). The frequency and pulse amplitude of square wave voltammograms were 2 Hz and 25 mV, respectively.
